System and method for generating treatment patterns

ABSTRACT

System and method for generating patterns P of aiming and treatment light on target eye tissue (e.g. the retina) of a patient&#39;s eye. The system includes light sources for treatment and aiming light, a scanner for generating patterns of spots of the generated light, a controller, and a graphic user interface that allows the user to select one of several possible spot patterns, adjust the spot density and/or spot size, and apply patterns with fixed or varied density. The patterns can be formed of interlaced sub-patterns and/or scanned without adjacent spots being consecutively formed to reduce localized heating. Partially or fully enclosed exclusion zones within the patterns protect sensitive target tissue from exposure to the light.

This application claims the benefit of U.S. Provisional Application No.60/718,762, filed Sep. 19, 2005, and of U.S. Provisional Application No.60/758,169, filed Jan. 10, 2006, both of which are hereby incorporatedby reference.

FIELD OF THE INVENTION

The present invention relates to retinal photocoagulation, and moreparticularly to a system and method for patterned optical ophthalmictreatment.

BACKGROUND OF THE INVENTION

Presently, conditions such as diabetic retinopathy and age-relatedmacular degeneration are subject to photocoagulative treatment withvisible laser light. While this type of visible laser light treatmenthalts the progress of the underlying disease, it can be problematic. Forexample, because the treatment entails exposing the eye to visible laserlight for a long period of time (typically on the order of 100 ms),damage can be caused to the patient's sensory retina from the heat thatis generated. During the treatment, heat is generated predominantly inthe retinal pigmented epithelium (RPE), which is the melanin-containinglayer of the retina directly beneath the photoreceptors of the sensoryretina. Although light is absorbed in the RPE, this type of treatmentirreversibly damages the overlying sensory retina and negatively affectsthe patient's vision.

Another problem is that some treatments require the application of alarge number of laser doses to the retina, which can be tedious and timeconsuming. Such treatments call for the application of each dose in theform of a laser beam spot applied to the target tissue for apredetermined amount of time. The physician is responsible for ensuringthat each laser beam spot is properly positioned away from sensitiveareas of the eye that could result in permanent damage. Since sometreatments can require hundreds of laser beam spots to evenly treat thetarget tissue, the overall treatment time can be quite long and requiregreat physician skill to ensure an even and adequate treatment of theentire target tissue area.

To reduce the treatment time needed for retinal photocoagulation, asystem and method has been proposed for applying multiple laser spotsautomatically in the form of a pattern of spots, so that an area oftarget tissue is efficiently treated by multiple spots pre-positioned onthe tissue in the form of the pattern. See for example U.S. PatentPublication US2006/0100677. However, rapid delivery of multiple beamspots in patterns raises new issues. For example, localized heating canoccur with the rapid and consecutive delivery of adjacent beam spotswithin a pattern. Moreover, variations in the patterns are needed toprovide better exclusion zone and beam spot density control (both foreven density and variable density), as well as better system controlthrough a graphic user interface.

SUMMARY OF THE INVENTION

The present invention solves the aforementioned problems by providing asystem and method of automatic projection of spot patterns onto thetarget tissue. More particularly, a photomedical system for treatingtarget tissue includes a light source for generating a beam of light, ascanner assembly for translating the beam to form a pattern of spots ofthe light, a focusing element for focusing the pattern of spots on thetarget tissue, a controller for controlling the scanner assembly, and agraphic user interface connected to the controller that includes adisplay for displaying a configuration of the pattern of spots and fordisplaying a plurality of different pattern configurations to choosefrom for the pattern of spots in response to an activation of thedisplay.

A method of treating target tissue includes selecting a pattern of spotsfrom a plurality of different pattern configurations displayed on adisplay of a graphic user interface by activating the display,generating a beam of light, translating the beam to form the selectedpattern of spots of the light, and focusing the pattern of spots of thelight on the target tissue.

Other objects and features of the present invention will become apparentby a review of the specification, claims and appended figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of the scanning coagulation system.

FIG. 2 is a diagram of a pattern P of a single spot.

FIGS. 3A-3G are diagrams of symmetrical patterns P of spots.

FIGS. 4A-4F are diagrams of non-symmetrical patterns P of spots.

FIGS. 5A-5B are diagrams of patterns P of spots with fully enclosedexclusion zones.

FIGS. 6A-6B are diagrams of patterns P of spots with partially openexclusion zones.

FIG. 7 is a diagram of a circular pattern P of spots having a generallyuniform spot density.

FIG. 8 is a diagram illustrating the scanning order of a pattern P ofspots with adjacent spots scanned consecutively.

FIGS. 9A and 9B are diagrams illustrating adjacent spots from a singlepattern P separated into two different spot patterns.

FIG. 9C is a diagram illustrating the pattern P of spots resulting fromthe combination of patterns in FIGS. 9A and 9B.

FIGS. 10A-10B are diagrams of a pattern P of spots with adjacent spotshaving different sizes.

FIGS. 11A and 11B are diagrams illustrating two different scanningorders of a round pattern P of spots.

FIGS. 12A and 12B are diagrams illustrating two different scanningorders of a wedge shaped pattern P of spots.

FIGS. 13A and 13D are diagrams illustrating four separately scannedsub-patterns that together form scanned pattern P.

FIGS. 14A-14D are diagrams illustrating aiming patterns that eitherenclose the area in which the treatment pattern P of spots of will bepositioned or identify the center and outer extent of the treatmentpattern P.

FIGS. 15A-15D are diagrams illustrating aiming patterns that eitherenclose the area in which the treatment pattern P of spots of will bepositioned or identify the center and outer extent of the treatmentpattern P.

FIG. 16 is a diagram illustrating automatic generation of arc patterns.

FIG. 17 is a front view of a graphic user interface screen for operatingthe photocoagulation system.

FIG. 18 is a front view of the graphic user interface screen displayingmultiple possible pattern configurations from which to choose from.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is a system and method for generating patterns Pof aiming and treatment light on target eye tissue (e.g. the retina) ofa patient's eye. FIG. 1 depicts an ophthalmic slit lamp based scanningphotocoagulator 1, which is a non-limiting example of a photocoagulationsystem for creating and projecting aiming and/or treatment patterns ofspots onto a patient's retina R. System 1 includes a light sourceassembly 2 and a slit lamp assembly 3.

The light source assembly 2 includes a treatment light source 12 forgenerating an optical beam of treatment light 14, and an aiming lightsource 16 for generating an optical beam of aiming light 18. Treatmentbeam 14 from treatment light source 12 is first conditioned by lens 20,which is used in conjunction with a curved mirror 22 to preparetreatment beam 14 for input into an optical fiber bundle 24. Afterencountering lens 20, treatment beam 14 is sampled by partiallyreflecting mirror 26. The light reflected from mirror 26 is used as aninput for a photodiode 28 that monitors the output power of treatmentbeam 14, assuring that the light source 12 is operating at the desiredpower. A mirror 30 is used to steer treatment beam 14 onto mirror 22,which in turn directs treatment beam 14 onto moving mirror 32. Aimingbeam 18 from aiming light source 16 is directed onto moving mirror 32via mirrors 34 and 36.

Moving mirror 32 is preferably mounted on a galvanometric scanner (butcould also be moved by piezo actuators or other well know optic movingdevices), and moves to selectively direct treatment and aiming beams 14,18 to one of the optical fibers 24 a, 24 b, 24 c, 24 d of optical fiberbundle 24 at any given time, where lenses 42, 44 focus the treatment andaiming beams 14, 18 into the selected optical fiber(s). Preferably,moving mirror 32 is spaced one focal length away from lens 20 to providefor a telecentric scan condition (thus allowing for the injection oftreatment beam 14 into all the optical fibers 24 a-24 d on parallelpaths, which preserves the launch numerical aperture across the opticalfiber bundle 24). Adjacent to the optical fibers 24 a-24 d are beamdumps 38, 40, which provide convenient locations to “park” the treatmentbeam 14. Optical fibers 24 a-24 d are used to deliver the treatment andaiming beams 14, 18 from the light source assembly 2 to the slit lampassembly 3. An additional optical fiber 46 may be used to direct thetreatment and/or aiming beams 14, 18 to the patient via other means suchas an endoprobe or laser indirect ophthalmoscope (not shown).

Slit lamp assembly 3 includes an optical fiber input 50 (for receivingoptical fibers 24 a-24 d), a scanner assembly 52, a delivery assembly54, and a binocular viewing assembly 56. The optical fiber input 50preferably includes a unique optical conditioning system for each of theoptical fibers 24 a-24 d, so that each optical fiber can produce aspecific (and preferably unique) spot size at the image plane IP of theslit lamp assembly 3. For example, light from optical fiber 24 a firstencounters a lens 58 a that collimates the light, followed by anaperture 60 that serves to reduce the effective numerical aperture byobscuring all but the central portion of the light beam. Light fromoptical fibers 24 b through 24 d first encounter lenses 58 b through 58d, respectively. Lenses 58 b-58 d are preferably configured to createdifferent spot sizes at the image plane IP, and subsequently at thetarget tissue (retina R). In the illustrated example, optical fibers 24a and 24 b have the same core diameter, but are made to create differentspot sizes by using different lenses 58 a and 58 b. Optical fibers 24 cand 24 d have different core diameters. It is preferable (but notnecessary) that all optical fibers deliver light with the same numericalaperture. Therefore, to keep the operating numerical apertures identicalfor these different channels, aperture 60 is used to counteract thechange in optical power of lens 58 a relative to lenses 58 b, 58 c, 58d.

The optical output of each optical fiber 24 a-24 d after conditioning bythe associated optical systems (e.g. lenses 58 a-58 d, aperture 60,etc.) is directed to the scanner assembly 52, which includes two movablemirrors 62, 64 mounted to two galvanometers 66, 68 (although any wellknown optic moving device such as piezo actuators could be used).Mirrors 62, 64 are configured to rotate in two orthogonal axes to scan(i.e. translate) the incoming light to form any desired pattern P.Mirror 62 may be rotated to redirect the light from any given one of thefibers 24 a-24 d into the remainder of slit lamp assembly 3, thus actingto “select” the output from that optical fiber while prohibiting anylight from the other optical fibers to continue through the entire slitlamp assembly 3. Because the output ends of optical fibers 24 a-24 d arenot coincident, mirror 62 must be rotated into position to intercept thelight from the desired optical fiber and transmit that light to mirror64, which can further move the light in an orthogonal axis. Thisconfiguration has the added benefit of preventing any stray light thatmay be delivered by the non-selected optical fibers from exiting thesystem. In FIG. 1, optical fiber 24 b is shown as the selected fiber,where the output of this fiber is scanned by mirrors 62, 64 to create ascanned pattern of light that travels through the rest of the system.

The scanned pattern of light P (which originates from treatment lightsource 12 and/or aiming light source 14) leaving the scanner assembly 52passes through the delivery assembly 54, which includes lens 70 (forcreating the intermediate scanned pattern at image plane IP), lens 72(for conditioning the light pattern for focusing into the eye), mirror74 (for directing the light pattern toward the target eye tissue), lens76 (preferably an infinity-corrected microscope objective lens) and lens78 (preferably a contact lens that provides final focusing of thepattern of light P onto the target eye tissue such as the retina R).Illumination source 80 (such as a halogen light bulb) is used toilluminate the target eye tissue R so that the physician can visualizethe target eye tissue.

The user (i.e. physician) views the target eye tissue R directly via thebinocular viewing assembly 56, which includes magnification optics 82(e.g. one or more lenses used to magnify the image of the target eyetissue, and preferably in an adjustable manner), an eye safety filter 84(which prevents potentially harmful levels of light from reaching theuser's eye, and which may be color-balanced to provide for aphotopically neutral transmission), optics 86, and eyepieces 88.

Pattern P of light is ultimately created on the retina of a patient Rusing optical beams 14, 18 from treatment light source 12 and aiminglight source 16 under the control of control electronics 90 and centralprocessing unit (CPU) 92. Control electronics 90 (e.g. fieldprogrammable gate array, etc.) and CPU 92 (e.g. a dedicatedmicroprocessor, a stand-alone computer, etc.) are connected to variouscomponents of the system by an input/output device 94 for monitoringand/or controlling those components. For example, control electronics 90and/or CPU 92 monitor photodiode 28 (to ensure treatment beam 14 isgenerated at the desired power level), operate the light sources 12, 16(turn on/off, set power output level, etc.), operate mirror 32 (toselect which optical fiber will be used for treatment and/or aimingbeams 14, 18), and control the orientations of galvanometric scanners66, 68 to produce the desired pattern P on the target eye tissue. CPU 92preferably serves to support control electronics 90, and serves as inputfor a graphical user interface (GUI) 96 and an alternate user inputdevice 98. GUI 96 allows the user to command various aspects of thesystem, such as the delivered spot size and pattern, pulse duration andoptical power output from treatment light source 12 and aiming lightsource 16. In addition to the user physically moving slit lamp assembly3 for gross alignment, the ultimate fine alignment of the light patternP on the target tissue may be further controlled by use of the inputdevice 98 (which can be a joystick, a touchpad, etc.), which causesmirrors 62, 64 alter their rotations when scanning the light beam thustranslating the entire pattern P on the target tissue. This approachyields very fine control of the disposition of the scanned beam.Additional input devices 98 can be included, such as knobs to adjust theoutput power of the light sources 12, 16, a footswitch or other type ofactivation device to activate the application of the aiming patternand/or treatment pattern, etc. The ultimate disposition of the opticaloutput of light sources 12, 16 is intended to be the pattern P containedin the patient's retina R.

The most basic types of patterns P are those formed of discrete,uniformly sized and uniformly spaced fixed spots. The user can use GUI96 to select, modify, and/or define a number of pattern variables, suchas: spot size, spot spacing (i.e. spot density), total number of spots,pattern size and shape, power level, pulse duration, etc. In response,the CPU 92 and control electronics 90 control the treatment light source12 (assuming it is a pulsed light source) or additionally a shutteringmechanism (not shown) somewhere along the beam 14 to create pulsedtreatment light. Mirrors 62, 64 move between pulses to direct each pulseto a discrete location to form a stationary spot. FIG. 2 shows a patternP having a single spot 100. FIGS. 3A-3G show fully symmetrical (i.e.symmetrical in both the vertical and horizontal axes) square or circularpatterns P of spots 100. FIGS. 4A-4D show non-symmetrical patterns P ofspots 100 such as lines, rectangles and ellipses. FIGS. 5A-5B showpatterns P of spots 100 with completely enclosed exclusion zones 102,which are zones within the pattern P that are free of spots-100. FIGS.6A-6B show patterns P of spots 100 with partially open exclusion zones102, where the exclusion zone 102 is not completely surrounded by thespots 100. Different patterns are ideal for different treatments. Forexample, a single spot pattern is ideal for titrating the power fortreatment, performing touchups to space between pattern spots, andsealing individual micro-aneurysms. Rectangle, square and line patternsare ideal for PRP (panretinal photocoagulation). Elliptical and circularpatterns are ideal for treating the macula, and sealing tears. Arcpatterns (i.e. circular or elliptical wedge patterns but without aradially center portion as shown in FIG. 4F) are ideal for partiallysurrounding and treating a tear, as well as for PRP treatment forperiphery and lattice degeneration. Patterns with enclosed exclusionzones are ideal for treating around sensitive areas such as the foveawhere it is important that the sensitive area not receive any treatmentlight. Patterns with partially open exclusion zones are ideal fortreating sensitive areas that are connected to other sensitive areas,such as avoiding treatment of both the fovea and the optic nerve thatextends from the fovea—see especially pattern P in FIG. 6A)

FIG. 7 illustrates a circular pattern P with a substantially uniformspot density. With rectangular shaped patterns, uniform spot densityover the entire pattern P is easily achieved by making the rows andcolumns equally spaced apart and spots 100 all the same size. However,with a circular pattern, uniformity is not easily achieved. Formingconcentric circles of spots with the same number of spots in each circlewill result in a reduced spot density as the radius increases.Therefore, the following criteria has been developed to maximize theuniformity of the spot density of a circular pattern P of spots 100(where the following calculations are preferably performed by the CPU92):

-   -   1) Spots 100 are positioned in N circles of different radii all        concentrically positioned around a single central point.    -   2) The diameter D(n) of the nth circle of pattern P (where n=1,        2, . . . N, and n=1 is the circle closest to the center) is:        D(n)=EZ+S _(D)+(n−1)×S _(D)(1+Round(DF))  (1)    -    where EZ is the diameter of the desired exclusion zone if any        (i.e. desired diameter of most inner circle), S_(D) is the        diameter of the spots, and Round(DF) is the density factor DF        rounded (up or down) to the nearest whole number. The density        factor DF is a number preferably selected or adjusted by the        user via the system GUI 96. Typical density factors for eye        surgery can be in the low single digits. If no exclusion zone is        desired, then n=2, 3, . . . N, and n=2 is the circle closest to        the center    -   3) The number of spots 100 in the nth circle of pattern P is:        $\begin{matrix}        {{{Number}(n)} = {8 \times {{Round}\left\lbrack {\pi \times {D(n)} \times \frac{1}{8} \times \frac{1}{S_{D}} \times \frac{1}{D\quad F}} \right\rbrack}}} & (2)        \end{matrix}$    -    where Round here is rounding (up or down) to the nearest whole        number.

4) If there is no exclusion zone EZ, then n=2, 3 . . . N, with n=2corresponding to the circle closest to the center.

These same equations can be utilized to form constant density concentricarcs of equal angular extent A along N concentric circles (e.g. seeFIGS. 4F, 6A, 6B). For calculating the diameter of the circle on whichthe arcs lie, equation (1) is the same, where A is the angular extent ofthe arcs and is between 0 and 2π. The number of spots in each concentricarc is (i.e. equation (2) becomes): $\begin{matrix}{{{Number}(n)} = {8 \times {{Round}\left\lbrack {\pi \times {D(n)} \times \frac{1}{8} \times \frac{1}{S_{D}} \times \frac{1}{DF} \times \frac{A}{2\pi}} \right\rbrack}}} & (3)\end{matrix}$

The most straight forward technique for scanning spots 100 in a patternP is sequentially where adjacent spots are scanned consecutively fromone end of the pattern to the other to minimize the amount of scanningmirror movement between spots (as illustrated in FIG. 8). However,exposing two adjacent spots consecutively (one just after the other) mayresult in undesirable localized heating. Thus, interlaced patterns canbe used to minimize localized heating. Interlaced patterns are patternsthat overlap each other in an alternating manner, so that the patternsthemselves overlap each other, but the spots of one pattern do notoverlap the spots of the other pattern (i.e. spots of one pattern arepositioned among the spots of the other in an alternating or intermixedmanner). FIGS. 9A and 9B represent how a pattern P (illustrated in FIG.9C) can be split up into two separate patterns P₁ and P₂ of alternatingspots, so that spots immediately adjacent to each other in the pattern Pare scanned onto the target tissue in two separate patterns (and thusmore separated in time). In the particular example of FIGS. 9A-9C,pattern P₁ represents half of the total spots in pattern P, and patternP₂ represents the same pattern as pattern P₁ except it is rotated by asmall angle (e.g. 11.25 degrees). Thus pattern P₁ of FIG. 9A is scannedin its entirety, then pattern P₂ of FIG. 9B is scanned in its entiretyin an interlaced fashion relative to pattern P₁, thus resulting inpattern P of FIG. 9C that induces less localized heating during its scanonto the target tissue.

FIG. 10A illustrates a variation of the interlacing of the two patternsP₁ and P₂ to result in pattern P. In this configuration, the size ofspots 100 forming pattern P₂ is smaller than that of the spots 100forming pattern P₁. Thus, in the combined pattern P, adjacent spots havedifferent sizes. This has the advantage of preserving more of theuntreated retina and maintaining open space for subsequent follow-uptreatment(s) (i.e. variable dosing). FIG. 10B is a variation on FIG.10A, in which the spot size is consistent within the same ring, but spotsizes from one ring to the next can vary.

FIGS. 11A-11B illustrate how varying the spot sequencing can be used tobalance control of localized heating with other considerations. In FIG.11A, the sequence in which each spot is scanned is numbered. Thus, thefirst eight pulses are used to consecutively scan the eight spots thatform the innermost circle. Then, the next most innermost circle isconsecutively scanned, and so on. Each circle is scanned in a singledirection with adjacent spots being scanned in consecutive order. Theadvantage of this pattern sequence is that the innermost circle closestto the exclusion zone 102 is scanned first, so that if the patient's eyemoves later on while the pattern is still being scanned, the beam atthat point in the treatment will be further away from the sensitive eyetissue in the exclusion zone and thus will minimize the risk ofinadvertent exposure to this tissue (e.g. the fovea). It should be notedthat this spot sequence results in adjacent spots in each circle beingscanned consecutively, which may result in undesirable localizedheating. In FIG. 11B, the spot sequence is modified so that each circleis scanned one at a time starting with the innermost circle, but withineach circle adjacent spots are not scanned consecutively (i.e. adjacentpulses in the beam are not used to scan adjacent spots in the finalpattern). This can entail either a random ordering, or a more orderlysequence such as scanning every other spot as the beam traverses aroundthe circle (as shown in FIG. 11B).

FIGS. 12A and 12B show pulse sequencing similar to that of FIGS. 11A and11B, except as applied to a wedge shaped pattern P. Specifically, inFIG. 12A, arcs of different radii are scanned one arc at a time, inorder, starting from the innermost circle. In FIG. 12B, the spots 100 ofthe wedge shaped pattern P are scanned randomly both within as well asamong the different arcs.

FIGS. 13A-13D show how a larger pattern P can be broken up intosub-patterns. Specifically, instead of scanning the entire pattern P (inthis example a circular pattern), it may be preferable to break up thepattern P into sub-patterns (in this example wedge-shaped quadrants),and scan each sub-pattern P₁, P₂, P₃, P₄ in its entirety before movingon to the next sub-pattern. Within each sub-pattern, the spots may bescanned out of order to minimize localized heating as discussed above.The advantage of this technique is that if the scanning were interruptedduring one sub-pattern (e.g. due to excessive eye movement), the systemcan better recover by simply moving on to the next sub-pattern. Tryingto resume a partially completed scan of a pattern may not be feasible insome applications once registration between the scanner and the targettissue is lost. In other words, it is easier to register the location ofan entire sub-pattern and continue rather than try to register thelocation of the remaining spots within a partially completed scannedpattern. By scanning the spots using sub-patterns to form an overallpattern P, and each sub-pattern is scanned without scanning adjacentspots consecutively, there is a good balance between small pattern localworking areas and avoidance of excessive localized heating.

There are various relationships that the aiming beam can take relativeto the treatment beam. For example, the aiming light can be projectedonto the target tissue in a pattern that generally matches that of thetreatment light (i.e. the system projects a pattern P of spots with theaiming light, followed by the projection of the pattern P of spots withthe treatment light overlapping the positions of the spots projected bythe aiming light). In this manner, the physician can align the pattern Pof treatment light spots knowing they will be positioned where thepattern P of alignment light spots are seen on the target tissue.Alternately, the aiming light can be scanned in a pattern P_(AIM) ofenclosed shape (e.g. circle, rectangle, ellipse, etc.), where thetreatment light pattern P of spots will be inside that enclosed shape(i.e. the pattern P_(AIM) of aiming light outlines the target tissuethat will receive the treatment light pattern P). Thus, P_(AIM) of FIG.14B outlines the pattern P of FIG. 14A, and P_(AIM) of FIG. 15B outlinesthe pattern P of FIG. 15A. In yet another example, the alignment patternP_(AIM) can identify the center of the treatment light pattern P ofspots, and possibly indicate the extent of the treatment light pattern Pof spots (e.g. alignment pattern P_(AIM) is cross hairs showing thecenter of the treatment light pattern P, with the outer ends of thecross hairs indicating the outer perimeter of the treatment lightpattern P. Thus, P_(AIM) of FIGS. 14C and 14D identify the center andextent of the pattern P of FIG. 14A, and P_(AIM) of FIGS. 15C and 15Didentify the center and extent of the pattern P of FIG. 15A.

FIG. 16 illustrates how the system can automatically generate patternsizes that exceed the scan size capabilities of the system. In FIG. 16,the desired pattern P is in the shape of a circular arc, with foursub-arc patterns 1-4. The system can be set to allow the user to definethe innermost sub-arc pattern 1 as a first scan, where the system willproceed to scan sub-arc pattern 1, and then automatically identify andscan in sequential order sub-arc patterns 2, 3, 4 which are disposedradially outwardly from the sub-arc pattern 1. With this configuration,a user can define an arc shaped pattern that approaches the scan limitsof the system, and the system will automatically scan additionalsub-patterns disposed radially outwardly from the pattern identified bythe user.

FIG. 17 illustrates an exemplary graphic user interface (GUI) 96 forselecting and implementing the above described photocoagulationpatterns. The illustrated GUI 96 comprises a touch screen display 110,which defines soft keys on the screen can be used to change theoperating conditions of the system. For example, the display 110 definessoft keys for adjusting aim beam power 112, fixation light power 114,exposure time 116, treatment power 118, spot density 120, pattern 122,and spot diameter 124. Touching these soft keys allows the user toadjust the selected parameter(s). Some soft keys are in the form ofup/down arrows, which allow the user to directly adjust the numericvalue. Other soft keys provide multiple options (e.g. spot density 120)from which the user can select the desired option. Still other soft keysillustrate an operating parameter, and when activated open new menusfrom which to manipulate that operating parameter (e.g. the pattern softkey 122 illustrates the configuration of the selected pattern such asspot spacing and pattern shape and layout, and when activated such asbeing touched opens a menu for selecting from a plurality of predefinedpatterns as illustrated in FIG. 18, or for defining a new pattern; thespot diameter soft key 124 indicates the size of the spots and whentouched opens a menu for adjusting the spot size). Status indicators arealso provided on display 110 (e.g. status indicator 126 indicateswhether the system is in a standby mode, an aiming light mode, or atreatment light mode; counter indicator 128 keeps track of the number oftreatment applications and can be reset by touching the reset soft key130). Soft keys can also be tailored to the specific data being input.For example, by dragging the user's finger around pattern soft key 122allows the user to select how many quadrants, octants, etc. that will beincluded in a circular pattern (e.g. dragging around the pattern key 122for approximately 310 degrees will select a pattern with sevenoctants—i.e. one octant will be left out of an otherwise completecircular pattern).

As used herein, the terms “comprises,” “comprising,” “includes,”“including,” “has,” “having” or any other variation thereof, areintended to cover a non-exclusive inclusion. For example, a process,method, article, or apparatus that comprises a list of elements is notnecessarily limited to only those elements but may include otherelements not expressly listed or inherent to such process, method,article, or apparatus. Further, unless expressly stated to the contrary,“or” refers to an inclusive or and not to an exclusive or. For example,a condition A or B is satisfied by any one of the following: A is true(or present) and B is false (or not present), A is false (or notpresent) and B is true (or present), and both A and B are true (orpresent).

It is to be understood that the present invention is not limited to theembodiment(s) described above and illustrated herein, but encompassesany and all variations falling within the scope of the appended claims.For example, while many of the patterns P described above andillustrated in the figures have a uniform spot density configuration,the present invention is not so limited. The spot density can be variedin the same pattern P in various ways. For example, the sizes and/orseparation of spots 100 in one portion of the pattern P can be differentthan that in another portion of the same pattern P. Treatment densitycan also be varied in the same pattern P, by varying the power and/orpulse duration that form spots in one portion of the pattern P relativeto the power and/or pulse duration that spots in another portion ofpattern P. Pattern P can not only be formed of discrete stationary spotsas described above, but also by one or more moving spots that formscanned lines or other scanned images. The aiming light source (oranother light source) can be used to project a fixation pattern on theeye along with the aiming pattern P and/or the treatment pattern P togive the patient a reference point to keep the eye still duringtreatment. The above system is ideal for, but not limited to,photocoagulation diagnosis/treatment. Lastly, as is apparent from theclaims and specification, not all method steps necessarily need beperformed in the exact order illustrated or claimed, but rather in anyorder that allows for the proper alignment and projection of thetreatment pattern P.

1. A photomedical system for treating target tissue, comprising: a light source for generating a beam of light; a scanner assembly for translating the beam to form a pattern of spots of the light; a focusing element for focusing the pattern of spots on the target tissue; a controller for controlling the scanner assembly; and a graphic user interface connected to the controller that includes a display for displaying a configuration of the pattern of spots and for displaying a plurality of different pattern configurations to choose from for the pattern of spots in response to an activation of the display.
 2. The photomedical system of claim 1, wherein the display of the graphic user interface is a touch sensitive screen.
 3. The photomedical system of claim 1, wherein the pattern of spots comprises at least first and second sub-patterns of the spots which are interlaced together to form the pattern of spots.
 4. The photomedical system of claim 3, wherein the spots in the first sub-pattern have a diameter that is greater than that of the spots in the second sub-pattern.
 5. The photomedical system of claim 3, wherein the controller causes the scanner assembly to entirely form the first sub-pattern before entirely forming the second sub-pattern.
 6. The photomedical system of claim 5, wherein the first and second sub-patterns of the spots are the same.
 7. The photomedical system of claim 6, wherein the first sub-pattern is positionally shifted relative to the second sub-pattern.
 8. The photomedical system of claim 6, wherein the second sub-pattern is positionally rotated by a predetermined angle relative to the first sub-pattern.
 9. The photomedical system of claim 1, wherein the scanner assembly forms the spots of light sequentially and in an order that avoids spots adjacent to each other in the pattern from being formed consecutively.
 10. The photomedical system of claim 1, wherein the pattern is generally round in shape and has a generally constant density of the spots.
 11. The photomedical system of claim 1, wherein the spots in the pattern are positioned in N concentric circles each having a diameter D defined as: D(n)=EZ+S _(D)+(n−1)×S _(D)(1+Round(DF)) wherein: D(n) is the diameter of the nth concentric circle of the pattern with n=1, 2, . . . N, EZ is a diameter of an exclusion zone in a center of the pattern, S_(D) is a diameter of the spots, and Round (DF) is a density factor DF rounded up or down to the nearest whole number.
 12. The photomedical system of claim 11, wherein each of the n=1, 2, . . . N concentric circles includes a predetermined number(n) of the spots according to: ${{Number}(n)} = {8 \times {{Round}\left\lbrack {\pi \times {D(n)} \times \frac{1}{8} \times \frac{1}{S_{D}} \times \frac{1}{DF}} \right\rbrack}}$ wherein Round[ ] means rounding up or down to the nearest whole number.
 13. The photomedical system of claim 1, wherein the spots in the pattern are positioned in N concentric circles each having a diameter D defined as: D(n)=S _(D)+(n−1)×S _(D)(1+Round(DF)) wherein: D(n) is the diameter of the nth concentric circle of the pattern with n=2, 3, . . . N, S_(D) is a diameter of the spots, and Round(DF) is a density factor DF rounded up or down to the nearest whole number.
 14. The photomedical system of claim 13, wherein each of the n=2, 3, . . . N concentric circles includes a predetermined number(n) of the spots according to: ${{Number}(n)} = {8 \times {{Round}\left\lbrack {\pi \times {D(n)} \times \frac{1}{8} \times \frac{1}{S_{D}} \times \frac{1}{DF}} \right\rbrack}}$ wherein Round[ ] means rounding up or down to the nearest whole number.
 15. The photomedical system of claim 1, wherein the spots in the pattern are positioned in arcs of equal angular extent A along N concentric circles each having a diameter D defined as: D(n)=EZ+S _(D)+(n−1)×S _(D)(1+Round(DF)) wherein: D(n) is the diameter of the nth concentric circle of the pattern with n=1, 2, . . . N, EZ is a diameter of an exclusion zone in a center of the pattern, S_(D) is a diameter of the spots, Round (DF) is a density factor DF rounded up or down to the nearest whole number, and A is the angular extent of the arcs and is between 0 and 2π.
 16. The photomedical system of claim 15, wherein each of the n=1, 2, . . . N concentric arcs includes a predetermined number(n) of the spots according to: ${{Number}(n)} = {8 \times {{Round}\left\lbrack {\pi \times {D(n)} \times \frac{1}{8} \times \frac{1}{S_{D}} \times \frac{1}{DF} \times \frac{A}{2\pi}} \right\rbrack}}$ wherein Round[ ] means rounding up or down to the nearest whole number.
 17. The photomedical system of claim 1, wherein the spots in the pattern are positioned in arcs of equal angular extent A along N concentric circles each having a diameter D defined as: D(n)=S _(D)+(n−1)×S _(D)(1+Round(DF)) wherein: D(n) is the diameter of the nth concentric circle of the pattern with n=2, 3, . . . N, S_(D) is a diameter of the spots, Round(DF) is a density factor DF rounded up or down to the nearest whole number, and A is the angular extent of the arcs and is between 0 and 2π.
 18. The photomedical system of claim 17, wherein each of the n=2, 3, . . . N concentric arcs includes a predetermined number(n) of the spots according to: ${{Number}(n)} = {8 \times {{Round}\left\lbrack {\pi \times {D(n)} \times \frac{1}{8} \times \frac{1}{S_{D}} \times \frac{1}{DF} \times \frac{A}{2\pi}} \right\rbrack}}$ wherein Round[ ] means rounding up or down to the nearest whole number.
 19. The photomedical system of claim 1, wherein the pattern has a density of the spots with the pattern that varies.
 20. The photomedical system of claim 1, wherein the pattern is an arc pattern, and wherein the controller causes the scanner to automatically scan the arc pattern and additional arc patterns radially outward from the arc pattern.
 21. The photomedical system of claim 1, wherein the spots have varying diameters in the pattern.
 22. The photomedical system of claim 1, further comprising: an aiming light source for generating an aiming beam of aiming light, wherein the scanner assembly is configured for translating the aiming beam to form an enclosed aiming pattern of the aiming light on the target tissue in which the pattern of spots is to be confined.
 23. The photomedical system of claim 1, further comprising: an aiming light source for generating an aiming beam of aiming light, wherein the scanner assembly is configured for translating the aiming beam to form an aiming pattern of the aiming light on the target tissue that indicates a center position of the pattern of spots.
 24. The photomedical system of claim 23, wherein the aiming pattern further indicates an outer boundary in which the pattern of spots is to be confined.
 25. The photomedical system of claim 24, wherein the aiming pattern comprises two or more crossed lines.
 26. The photomedical system of claim 1, wherein the pattern of spots defines a partially enclosed exclusion zone on the target tissue in which the spots are not incident.
 27. The photomedical system of claim 1, wherein the pattern of spots comprises a plurality of arc patterns separated from each other.
 28. A method of treating target tissue, comprising: selecting a pattern of spots from a plurality of different pattern configurations displayed on a display of a graphic user interface by activating the display; generating a beam of light; translating the beam to form the selected pattern of spots of the light; and focusing the pattern of spots of the light on the target tissue.
 29. The method of claim 28, wherein the display of the graphic user interface is a touch sensitive screen.
 30. The method of claim 28, wherein the pattern of spots comprises at least first and second sub-patterns of the spots which are interlaced together to form the pattern of spots.
 31. The method of claim 30, wherein the spots in the first sub-pattern have a diameter that is greater than that of the spots in the second sub-pattern.
 32. The method of claim 30, wherein the translating of the beam comprises: forming the first sub-pattern; and forming the second sub-pattern only after the forming of the first sub-pattern.
 33. The method of claim 32, wherein the first and second sub-patterns of the spots are the same.
 34. The method of claim 33, wherein the first sub-pattern is positionally shifted relative to the second sub-pattern.
 35. The method of claim 33, wherein the second sub-pattern is positionally rotated by a predetermined angle relative to the first sub-pattern.
 36. The method of claim 28, wherein the translating of the beam results in forming the spots of the light sequentially and in an order that avoids spots adjacent to each other in the pattern from being formed consecutively.
 37. The method of claim 28, wherein the pattern is generally round in shape and has a generally constant density of the spots.
 38. The method of claim 28, wherein the spots in the pattern are positioned in N concentric circles each having a diameter D defined as: D(n)=EZ+S _(D)+(n−1)×S _(D)(1+Round(DF)) wherein: D(n) is the diameter of the nth concentric circle of the pattern with n=1, 2, . . . N, EZ is a diameter of an exclusion zone in a center of the pattern, S_(D) is a diameter of the spots, and Round (DF) is a density factor DF rounded up or down to the nearest whole number.
 39. The method of claim 38, wherein each of the n=1, 2, . . . N concentric circles includes a predetermined number(n) of the spots according to: ${{Number}(n)} = {8 \times {{Round}\left\lbrack {\pi \times {D(n)} \times \frac{1}{8} \times \frac{1}{S_{D}} \times \frac{1}{DF}} \right\rbrack}}$ wherein Round[ ] means rounding up or down to the nearest whole number.
 40. The method of claim 28, wherein the spots in the pattern are positioned in N concentric circles each having a diameter D defined as: D(n)=S _(D)+(n−1)×S _(D)(1+Round(DF)) wherein: D(n) is the diameter of the nth concentric circle of the pattern with n=2, 3, . . . N, S_(D) is a diameter of the spots, and Round(DF) is a density factor DF rounded up or down to the nearest whole number.
 41. The method of claim 40, wherein each of the n=2, 3, . . . N concentric circles includes a predetermined number(n) of the spots according to: ${{Number}(n)} = {8 \times {{Round}\left\lbrack {\pi \times {D(n)} \times \frac{1}{8} \times \frac{1}{S_{D}} \times \frac{1}{DF}} \right\rbrack}}$ wherein Round[ ] means rounding up or down to the nearest whole number.
 42. The method of claim 28, wherein the spots in the pattern are positioned in concentric arcs of equal angular extent A along N concentric circles each having a diameter D defined as: D(n)=EZ+S _(D)+(n−1)×S _(D)(1+Round(DF)) wherein: D(n) is the diameter of the nth concentric circle of the pattern with n=1, 2, . . . N, EZ is a diameter of an exclusion zone in a center of the pattern, S_(D) is a diameter of the spots, Round (DF) is a density factor DF rounded up or down to the nearest whole number, and A is the angular extent of the arcs and is between 0 and 2π.
 43. The method of claim 42, wherein each of the n=1, 2, . . . N concentric arcs includes a predetermined number(n) of the spots according to: ${{Number}(n)} = {8 \times {{Round}\left\lbrack {\pi \times {D(n)} \times \frac{1}{8} \times \frac{1}{S_{D}} \times \frac{1}{DF} \times \frac{A}{2\pi}} \right\rbrack}}$ wherein Round[ ] means rounding up or down to the nearest whole number.
 44. The method of claim 28, wherein the spots in the pattern are positioned in concentric arcs of equal angular extent A along N concentric circles each having a diameter D defined as: D(n)=S _(D)+(n−1)×S _(D)(1+Round(DF)) wherein: D(n) is the diameter of the nth concentric circle of the pattern with n=2, 3, . . . N, S_(D) is a diameter of the spots, Round(DF) is a density factor DF rounded up or down to the nearest whole number, and A is the angular extent of the arcs and is between 0 and 2π.
 45. The method of claim 44, wherein each of the n=2, 3, . . . N concentric arcs includes a predetermined number(n) of the spots according to: ${{Number}(n)} = {8 \times {{Round}\left\lbrack {\pi \times {D(n)} \times \frac{1}{8} \times \frac{1}{S_{D}} \times \frac{1}{DF} \times \frac{A}{2\pi}} \right\rbrack}}$ wherein Round[ ] means rounding up or down to the nearest whole number.
 46. The method of claim 28, wherein the pattern has a density of the spots within the pattern that varies.
 47. The method of claim 28, wherein the pattern is an arc pattern, and wherein the method further comprises: translating the beam to form additional arc patterns radially outward from the arc pattern; and focusing the additional arc patterns of spots of the light on the target tissue.
 48. The method of claim 28, wherein the spots have varying diameters in the pattern.
 49. The method of claim 28, further comprising: generating an aiming beam of aiming light; translating the aiming beam to form an enclosed aiming pattern of the aiming light on the target tissue in which the pattern of spots is to be confined.
 50. The method of claim 28, further comprising: generating an aiming beam of aiming light; and translating the aiming beam to form an aiming pattern of the aiming light on the target tissue that indicates a center position of the pattern of spots.
 51. The method of claim 50, wherein the aiming pattern further indicates an outer boundary in which the pattern of spots is to be confined.
 52. The method of claim 50, wherein the aiming pattern comprises two or more crossed lines.
 53. The method of claim 28, wherein the pattern of spots defines a partially enclosed exclusion zone on the target tissue in which the spots are not incident.
 54. The method of claim 28, wherein the pattern of spots comprises a plurality of arc patterns separated from each other. 